Scientific name: Terrapene carolina carolina
Common name: The Eastern Box Turtle
(Information for this species page was compiled in part by Nicole Lenninger for
Biology 220 at Penn State New Kensington, Spring 2002)
The eastern box turtle is a familiar and easily recognized inhabitant of the Nature Trail ecosystem. Box turtles are long lived animals that are relatively slow in reproducing. They reach sexual maturity only after four or five (or possibly twenty!) years of life, produce relatively small numbers of eggs, and have a high hatchling mortality rate. Their numbers in the wild have, unfortunately, been steadily declining both due to habitat destruction and to the over collection of individuals for pets. It is hoped that protected habitats like the Nature Trail and increased awareness by the general public will be sufficient to allow this species to maintain itself as a viable component of our Western Pennsylvanian ecosystems.
The eastern box turtle is small (4.5 to 6 inches shell width, up to eight inch shell length), land turtle with a high, dome-like upper shell ("carapace"). Younger box turtles can be distinguished by their flatter carapaces. The carapace can have quite a variety of colors and patterns ranging from a smooth, highly camouflaged, green to a brightly marked, brownish black with yellow and orange highlights. The patterns of the markings on the carapaces of box turtles are often distinctive enough to allow identification of specific individuals within a population. The carapace also typically has a ridge (the "keel") down its centerline and flared edges (the "marginals").
The head and neck and legs of the eastern box turtle are also heavily patterned with distinctive yellow to orange and, occasionally, reddish streaks. Their under shells (the "plastrons") range in color from yellow-brown to brownish-black and are hinged to allow movement of the anterior and posterior sections. A box turtle is able to use these hinged plastron lobes to tightly close its head and tail openings. The fit of the closed hinged plastron against the carapace is so tight that not even the blade of a knife can be inserted between them. This ability to tightly encase their bodies within their shells provides the eastern box turtle with a very effective mechanism of defense. Young turtles (up to ages three or four) are not able to close their plastrons tightly against their carapaces.
It is quite easy to determine the sex of an eastern box turtle. Males (pictured
above) have concave plastrons, thicker based and longer tails, longer front claws, and bright red or orange eyes. Females have flat or slightly convex plastrons, short, thin tails, and dark red or brown eyes. Also, the "vent" opening (the common, "cloacal" opening of the lower digestive, urinary and reproductive tracts) in the male is typically found past the margin of the carapace while in the female it is located under the carapace edge.
Eastern box turtles live thirty to forty years in the wild and have been alleged to reach ages of one hundred years or more in captivity. A box turtle grows very rapidly for the first four or five years of its life reaching sexual maturity in four years but full adult size only by age twenty. Some have stated that only fully grown box turtles, in spite of apparent earlier sexual maturity, are actually reproductively active.
Habitat, Activity and Hibernation
Eastern box turtles are found from New Hampshire to Georgia, and west to Michigan, Illinois and Tennessee. They prefer open woodlands, pastures, and marshy meadows. They are most likely to be found in moist habitats and spend a great deal of their time buried in the leaves and surface soils and hidden in the brushy piles of their forest habitats. Their optimal environmental temperatures are between 70 and 85 degrees F, but they will tolerate nighttime temperatures down into the 50's. During the summer, they are seldom active during the mid-day heat and do most of their hunting and foraging during the cool, early morning hours. They often soak themselves in puddles, seeps, springs and other muddy places for hours or days at a time. As temperatures fall in the autumn, eastern box turtles enter into hibernation (usually starting in October or November) and burrow into loose soil, mud, or abandoned mammal burrows. As the soil temperatures drop with the coming winter season, the turtles burrow deeper and deeper into their hibernacula.
Eastern box turtles are predominantly carnivorous during their younger years and become more and more herbivorous as they age. Prey items taken by box turtles include, snails, worms, insects, spiders, frogs, snakes lizards, small mammals, and carrion. They also eat fruits, berries, leaves and many types of mushrooms. Some of the mushrooms consumed by box turtles are very toxic for humans, so it is inferred that the turtles are unaffected by these potential poisons. Humans eating box turtles that have recently fed on poisonous mushrooms may become quite ill due
to the toxins accumulated in the turtles' flesh.
Turtles will forage over an area the equivalent of two football fields over their lives. Adult individuals occupy "home ranges" of variable sizes (larger in less favorable habitats or in systems with relatively low population densities, smaller in more favorable or more densely populated habitats). Immature individuals (less than nine years of age) and many mature, but un-established males move extensively about as "transients." The directionality of their movements is, apparently, "one way," and quite energetically directional! (So, if you rescue a box turtle crossing a road ALWAYS put it over on the side to which it was heading!).
Box turtles are often found near to each other and can form range-overlapping, socially tolerant groups of three or four individuals. Fighting and other types of aggressive behavior are rare with the exception of occasional "sparring" matches (especially between
competing males) that involve alternative bouts of two individuals biting each other's shells with, obviously, little damage to either individual. Eastern box turtles walk with a steady, energetic stride holding their heads upright. They can travel 50 yards or more in a single day and
posess strong homing instincts that compel them to move in the direction of their home ranges.
Female box turtles are callable of storing sperm in their oviducts for up to four years and are thus able to produce viable eggs for many years following a single mating. They will mate between May and October. Eggs are laid into flask-shaped holes that are three to four inches deep. The holes are meticulously dug by the female into the soil of sunny, warm sites. Three to six elliptical, leathery eggs are laid and then covered to incubate and then hatch on their own. Several clutches can be laid per year. Incubation lasts two to three months. A clutch that hatches late in the season may over-winter in the nest hole and emerge the following spring.